Unit 4 Review, pages 570–577
Knowledge
1. c
2. c
3. d
4. b
5. c
6. d
7. c
8. d
9. d
10. a
11. d
12. c
13. d
14. b
15. a
16. d
17. c
18. a
19. c
20. True
21. False. Sweating in response to elevated temperature is and example of a response of negative
feedback.
22. True
23. False. Osmoregulation ensures that the intracellular and extracellular fluids are isoosmotic.
24. False. Nephrons are found in mammals.
25. True
26. False. The pineal gland secretes hormones that help regulate biological rhythms by
producing the hormone melatonin.
27. True
28. True
29. False. Type I diabetes must be treated by injections of insulin.
30. True
31. False. FSH is released in the pituitary gland in response to gonadotropin-releasing hormone
from the hypothalamus.
32. False. Schwann cells are special types of glial cells, which produce the myelin sheath.
33. False. The re-establishment of polarity in neurons is called repolarization.
34. False. Grey matter centred in the pons and medulla controls involuntary functions such as
heart rate and blood pressure.
35. False. There are 31 pairs of spinal nerves.
36. True
37. True
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Unit 4: Homeostasis U4-3
38. (a) iii
(b) v
(c) vi
(d) i
(e) vii
(f) viii
(g) ix
(h) ii
(i) x
(j) iv
39. (a) v
(b) i
(c) ii
(d) iii
(e) iv
40. (a) v
(b) iii
(c) ii
(d) iv
(e) i
41. The internal environment of the human body is made up of the extracellular fluid, which
consists of the interstitial fluid that fills the spaces between the cells and tissues, and the plasma
or fluid portion of the blood.
42. The fight-or-flight response is a positive feedback response. Adrenalin and other hormones
stimulate further release to make the animal more fit to run or fight.
43. (a) Hibernation and estivation are similar in that they are both a state of torpor.
(b) Hibernation and estivation are different in that hibernation occurs in the winter or colder
weather and estivation occurs in the summer when temperatures are high and food is scarce.
44. (a) Deamination is the removal of an amino group from an amino acid that comes from the
breakdown of protein.
(b) Deamination is an important process because the removal of the amino group allows the rest
of the amino acid to be used as an energy source.
45. Table 1
Structure Process
Description
Molecules
present
Bowman’s filtration
movement of fluids from the water, glucose, amino
capsule
glomerulus into Bowman’s
acids, salt, urea, uric
capsule.
acid
proximal
reabsorption
movement of molecules from active transport of
tubule
filtrate back into blood
glucose, amino acids,
sodium, osmosis of
water
distal
tubular
movement of molecules from uric acid, ammonia, H+
tubule
secretion
the blood to the nephron
ions
collecting excretion
urine collection
water, salts, urea, uric
duct
acid
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46. (a) ACE stands for Angiotensin-Converting Enzyme.
(b) ACE inhibitors are often prescribed to control high blood pressure.
47. Glands secrete hormones. Target cells are cells that have receptors for specific hormones and
react in their presence.
48. Answers may vary. Sample answer: Physiological changes that results from the release of
epinephrine and norepinephrine are: blood sugar levels increase, heart rate increases, breathing
rate increases, blood pressure increases, blood vessels and pupils dilate.
49. Diabetes insipidus, ADH
50. Anabolic steroids are not used primarily in aerobic sports because anabolic steroids build
muscle mass and muscle mass may not be an advantage in these sports.
51. Pituitary, FSH
52. Three types of neurons involved in the reflex arc are afferent neurons, interneurons, efferent
neurons.
53. (a) A—dendrites; B—cell body; C—axon; D—axon terminals; E—nucleus.
(b) brain, spinal cord, muscles, glands
(c) The dendrites receive the electrical impulse.
(d) D is an axon terminal, whose function is to connect with and enable signals to be transmitted
to the dendrites of other neurons or to an effector.
54. The part of the brain that plays a major role in motor responses and voluntary movements of
skeletal muscles is the cerebellum.
55. The name of this band of grey matter in the spinal cord that produces a neurotransmittor that
results in pain perception is the substantia gelatinosa.
56. The photoreceptors in the eye that are specialized for the detection of colours are the cones.
Understanding
57. The body system that regulates the concentrations of oxygen and carbon dioxide is the
nervous system.
58. The body changes the set point of its body temperature if you suffer from an infection. The
homeostatic effectors increase your body temperature causing a fever that will help fight off the
infection. Once the infection has cleared up, the set point is reset to normal.
59. The cell counters the forces of diffusion by using active transport to pump sodium and
potassium ions against the concentration gradient.
60. Many marine animals do not need to osmoregulate because the concentrations of their
intracellular and extracellular solutions are identical to that of their external environment.
61. (a) A—proximal convoluted tubule; B—distal convoluted tubule; C—glomerulus; D—
collecting duct; E—ascending segment of the loop of Henle; F—peritubular capillaries.
(b) I would expect to find the glomerular filtrate that is most similar to excreted urine in the
collecting duct (or possibly the distal tubule).
(c) I would expect to find the blood with the greatest concentration of urea in the glomerulus.
(d) Most of the water that passes into the glomerular filtrate is reabsorbed.
(e) An increase in blood pressure in the glomerulus would increase the filtration rate.
(f) In the proximal convoluted tubule, you would normally find glucose.
(g) In the glomerulus, but not the proximal convoluted tubule, you would normally find proteins.
62. Prohormones are hormones that are secreted in an inactive or less active form and are
converted by the target cells or by enzymes in the blood or other tissues to the active form.
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63.
64. ADH is produced by the hypothalamus and travels to the pituitary via specialized nerve cells.
65. In males, the pituitary secretes luteinizing hormone (LH). LH stimulates the interstitial cells
of the testes to produce testosterone; testosterone stimulates the development and maintenance of
the secondary sexual characteristics including growth of facial and body hair, muscle
development, changes in vocal chords, and development of sex drive.
66. Answers may vary. Synthetic hormones are used to treat asthma, rheumatoid arthritis, lupus,
organ rejection as a result of transplantation, and inflammatory skin disorders.
67. The order of events of the withdrawal reflex are: (d), (f), (a), (c), (g), (b), (e).
68. The lobe of the brain responsible for vision is the occipital lobe.
69. The autonomic nervous system (ANS) controls largely involuntary processes such as
digestion, secretion by sweat glands, circulation of the blood, many functions of the reproductive
and excretory systems, and the contraction of smooth muscles in all parts of the body.
70. (a) Endorphins are naturally occurring chemicals that the brain produces in higher than
normal amounts when the body is under stress or in pain.
(b) Endorphins reduce pain in the body by blocking the production of pain neurotransmitters. If
pain impulses cannot reach the brain, pain will not be felt.
Analysis and Application
71. Birth control pills reduce the chance of pregnancy because they contain estrogen and
progesterone, which have a negative feedback effect on gonadotropic hormone secretion.
Ovulation is prevented because luteinizing hormone is not secreted by the pituitary gland.
72. Shivering helps the body thermoregulate because it causes rapid cycling between relaxed and
contracted muscles. This generates heat. Shivering increases heat output by five to six times.
73. A drop in blood pressure would result in less urine production. Decreased blood pressure
results in less filtration from the glomerulus.
74. (a) Sample B is from a patient who has diabetes mellitus because their blood sugar levels are
high.
(b) Sample D is from a patient who has diabetes insipidus because their urea concentration is low
due to high water levels.
(c) Sample C is from a patient who has Bright’s disease because of high protein levels in the
blood.
75. (a) Under normal conditions, high pressure in the glomerulus results in water and dissolved
solutes entering the nephron.
(b) In a person with syphilis, pressure is higher than normal in the glomerulus, resulting in
proteins and larger molecules that normally would not enter the nephron, gaining access.
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(c) Dialysis could be used to treat a patient with syphilis because dialysis allows a patient’s blood
to be filtered to remove excess solutes and nitrogenous wastes. Blood is passed through a dialysis
machine filled with a solution that allows these materials to enter by diffusion.
(d) Answers will vary. Answers may include balancing the issues of equal health care, need, and
a person’s own responsibility for their choices.
76. A person would be dehydrated after consuming alcohol because alcohol slows the release of
ADH from the posterior pituitary gland. Decreased ADH levels decrease the amount of water
reabsorbed by the kidneys, increasing urine output. Therefore, more fluid is lost than taken in,
resulting in dehydration.
77. (a) Protein and unknown substances were not filtered by the nephron. They are too large to
pass through.
(b) The unknown substance may be red blood cells due to their relatively large size.
(c) Urea and ammonia levels increase after filtration occurs because water is reabsorbed and urea
and ammonia are not.
(d) Based on the data, the part of the nephron that ADH would act on is the collecting duct.
78. (a) She is most likely suffering from gestational diabetes.
(b) The rise in blood sugar occurs only after eating because the mother’s insulin production has
been interfered with by hormones produced during pregnancy. Gestational diabetes usually does
not occur until later in pregnancy, when the placenta is producing more of the hormones that
interfere with the mother’s insulin.
79. (a) These observations demonstrate the all-or-nothing response principle.
(b) This principle depends on the fact that the action potential either occurs or it does not. The
response of the neuron to an action potential depends on how many action potentials it transmits
and their frequency.
80. Both types of neurons are necessary because without both the system would either shut down
from lack of stimulation or be overloaded by too much stimulation.
81. The classmate is not correct. Neurons are individual cells, nerves are bundles of neurons.
82. The stimulated neurotransmitters are endorphins and serotonin.
83. Ear infections can cause swelling that can block the Eustachian tube, preventing the
equalization of pressure between the middle ear and the external environment. An airplane cabin
is pressurized, but the changes in pressure while taking off and landing create unequal pressures
between the middle ear and the air in the cabin. This pressure imbalance could cause the eardrum
to rupture, causing pain and hearing loss. Once the infection is cured, the Eustachian tube will be
able to function normally.
84. The senses of taste and smell are complementary. There are only five types of taste; what is
perceived as flavour is modified by olfactory input. The clogged nasal passages of a cold
decrease the contact of scent molecules with the receptors in the nose. What the person tastes is
only the simple tastes detected by the taste buds.
85. A small daily dose of ASA can reduce the risk of heart attack or stroke brought on by the
formation of blood clots in those suffering from atherosclerosis because aspirin can prevent the
production of prostaglandins that promote the clotting of blood.
/U A
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Unit 4: Homeostasis U4-7
Evaluation
86. Answers will vary. Sample answer: Infections cause fever, swelling, inflammation, and
sometimes nausea appear bad for the body. The symptoms are a combination of the lack of
homeostasis and your body's efforts to re-establish homeostasis. For example, a viral infection
causes an imbalance at the cell and tissue level through the toxic secretions from the virus. So, to
try to re-establish homeostasis, your body initiates an immune response. In this case, the immune
response is inflammation of the membranes around the lungs, and a localized increase in
temperature that helps kill the virus and the virally infected cells. The membranes around the
lungs are normally smooth and lubricated. However, when they become inflamed, it is very
painful. The inflammation is causing the painful friction. This friction causes a build-up of fluid
that results in breathing problems. Homeostasis has made things worse at this point but this is
where medical treatments can be helpful. They aid your body in returning to homeostasis by
trying to directly attack the cause of the problem, like antibiotics for bacterial infections or
vaccines for viruses.
87. Blood glucose levels are important for overall human health because body cells need an
adequate supply of glucose to function properly. If blood glucose levels are too low there is no
energy for the metabolism of the cells and if blood glucose levels are too high, particularly
chronically, it can damage peripheral nerves, skin, retinas, kidneys and other organs. Chronic
high blood glucose predisposes people to cardiovascular diseases and can create medical
emergencies (ketoacidosis and hyperglycemia).
88. Experimental designs, questions, hypotheses and variables will vary. Sample answer:
Testable question: What effect does the removal of the pituitary gland have on the production of
urine? Hypothesis: If the pituitary gland is removed urine production would increase because
ADH (the hormone responsible for reabsorption of water), which is produced in the pituitary
gland, would not be produced. Independent variable: removal of the pituitary gland. Dependent
variable: urine production. Controlled variables: diet, water consumption, age, gender, health of
rats, time.
89. (a) Based on the information, the endocrine gland likely involved is the adrenal medulla. The
adrenal medulla produces epinephrine, which is therefore the likely hormone involved. Target
cells for this hormone are found throughout the body explaining multi-system symptoms,
hormones travel quickly causing these reactions, and the nervous system is connected directly to
the medulla.
(b) A possible diagnosis is a stress reaction brought on by anxiety.
90. (a) My friend is incorrect. hGH is produced in large amounts by the anterior pituitary gland,
even in adults.
(b) I would tell my friend that even though she has stopped growing, she is still producing hGH
because it has other roles in the adult body. hGH increases fatty acid levels in blood, providing a
source of energy other than sugar for muscles. This helps maintain blood sugar levels for the
brain, which cannot use fat for energy, decreases fat stores in the body, and increases protein
synthesis boosting immunity.
91. Estrogen inhibits the growth of facial hair in women; if it has the same effect on men, it will
counter the action of testosterone in the development of facial hair. Estrogen promotes the
development of female secondary sexual characteristics; the same effect in males could result in
the growth of breasts, a delay in the deepening of the voice, and a decreased sex drive.
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Unit 4: Homeostasis U4-8
92. Acetylcholine has an enzyme that breaks it down because acetylcholine stimulates the neuron
to increase the size of its pores so that Na+ can enter the cell; if acetylcholine was not broken
down, it would collect in the synapses of the brain causing over-stimulation and eventually the
brain tissue would die.
93. The parasympathetic nervous system activity constricts the pupil of the eye. Atropine drops
are added so that the pupil remains open for examination with a bright light.
94. Answers will vary. Answers should include a description of the normal function of the organ
and its role in maintaining homeostasis. Answers should also include a detailed explanation of
how stress (the enemy) affects the function of the organ and how homeostatic mechanisms
function to return the organ function back to a normal state.
95. Poems will vary.
Reflect on Your Learning
96. Answers will vary. Sample answer: As humans, we subject our bodies to various stressors.
If there were no homeostatic mechanism, then the system would fall out of balance, and possibly
fail completely. The result is disease—a disruption in the ability of a body system or part to carry
out its normal function. By keeping our systems in homeostasis, we can protect ourselves against
disease and enjoy the benefits of health.
97. Answers will vary. Sample answer: Inhibition allows the suppression of sensory information
of a less-than-critical nature. The pressure of the chair against the body or the temperature of a
room do not require the same attention as analyzing the information appearing visually and the
coordination of gripping the pen and writing this response. Without inhibitory neurotransmitters,
sensory information would be overwhelming.
98. (a) Answers will vary. Sample answer: I think that for certain professions, such as police
officer, teacher, school bus driver, doctor, nurse, to name a few, pre-employment drug testing
should be mandatory. These types of professions require a large amount of responsibility and
only the candidates that demonstrate that they are not drug abusers should be hired.
(b) Answers may vary. Sample answer: I think that drug testing as part of the application process
could be quite costly. If an employer tested everyone who applied, then they would have less
money to pay employees etc. As such, I think that drug testing should be a condition of
employment, but it only needs to be administered once a job offer has been made and accepted.
(c) Answers will vary. Sample answer: I think that only some jobs should require drug-testing;
mainly those that carry a large amount of responsibility, for example, doctor, nurse, or police
officer.
(d) Answers will vary. Sample answer: Yes, I would be willing to take a drug test because I do
not use drugs and therefore, I have nothing to fear. Also, I think this is a fair practice and I would
not mind if I was asked to participate in this kind of testing.
99. (a) Answers will vary. Sample answer: Yes, I think that a biological passport created with
multiple samples over time is better than random urine testing. This is because random one-time
urine testing is more of a hit-and-miss situation. That is, an athlete may have used performance
enhancing drugs previously, but managed to clear them from their system prior to testing.
However, by taking samples over time, you can get a better long-term picture of the athlete’s
history with (or without) drugs.
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(b) Answers will vary. Sample answer: Yes, I think it is realistic to expect the science of antidoping to match the creation of performance-enhancing drugs and masking agents. If scientists
do not keep on top of these new methods of performance enhancement, eventually, athletes will
find ways to overcome the drug testing and the integrity of the sport will be lost.
(c) Answers will vary. Sample answer: Yes, I think a two year ban for a first doping offence is
reasonable, even in light of the relatively short career life of an athlete. By having such a large
ban for the first offense, it will likely discourage athletes from using the performance-enhancing
drugs at all.
(d) Answers will vary. Sample answer: Yes, I do think that a lifetime ban is an appropriate
punishment for a second offence. To have a second offence, the athlete must have had a first
offence (and a two year ban), and therefore they have had ample opportunity to reflect on their
mistake and cease usage of the performance-enhancing drug. If after this experience, they return
to using drugs, they clearly have not learned their lesson and likely never will.
Research
100. Reports may vary. Reports should include the following information: Stem cells are
unspecialized cells that have the ability to become other, more specialized cell types. By
inserting cells into damaged spinal or brain tissue, it is thought that these cells will copy those
around them and become new (undamaged) nerve cells. If the neural pathways can be reestablished, paralysis will be cured.
101. Fact sheets may vary. Fact sheets should include the following information:
• Kidney stones are the result of crystallization of minerals in the urine.
• Kidney stones are caused by too much of certain substances in the urine (for example, calcium)
and dehydration.
• Some people with kidney stones are asymptomatic, while others have severe back pain,
blocked urine flow, and severe pain as the stones pass through the urethra.
• Kidney stones are diagnosed by urinalysis, palpation of the abdomen, x-rays, CT scan, MRI,
and intravenous pyelogram (IVP) test.
• Treatment options for kidney stones include medications that can help break them up
depending on the substance, surgery, and extracorporeal shock waves.
• Kidney stones can be prevented by proper hydration.
• A doctor might recommend not consuming alcohol if you have a kidney stone because alcohol
causes dehydration.
• Doctors believe that an increase in the number of kidney stone cases is caused by fast food
diets (high sodium foods and colas that dehydrate), as well as not drinking enough water.
102. Reports will vary. Reports should include the following information:
• Osteoporosis is a progressive condition in which bones become structurally weak and more
likely to fracture or break.
• Bone mass reaches its maximum between the ages of 20 and 25. Osteoporosis begins when you
lose bone mass faster than your body can form new bone (generally around or after menopause
in women, although men lose bone mass as they age as well.
• Lack of estrogen in women and lack of testosterone and estrogen (small amounts) in men are
the hormones involved in osteoporosis.
• People at risk for osteoporosis are those with a family history of osteoporosis or hip fractures,
post-menopausal women, thin or small-framed people, Caucasians, and Asians.
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Unit 4: Homeostasis U4-10
• Factors that can increase your risk for bone loss include, anorexia, smoking, a lack of calcium,
drinking too much alcohol, and amenorrhea (missing periods).
• To avoid any osteoporosis, eat a balanced diet, do not smoke, get plenty of calcium, and do not
drink too much alcohol. People can also take calcium and vitamin D supplements, and should
exercise daily.
103. Posters will vary. Neurons that produce dopamine are destroyed. Therefore there is less of
this neurotransmitter chemical in the brain. Depending on which parts of the brain are affected,
there would be less neural transmission in specific areas. If the frontal lobe is affected, this may
result in slower movements and speech, reduced cognitive activity, and an altered personality. If
the parietal lobe is affected, the patient may have altered responses to temperature and touch. If
the temporal lobe is affected, there may be difficulties with hearing and memory. If the occipital
lobe is affected, the interpretation of visual information may be altered.
104. Reports will vary. Reports should include the following information:
• Anatomical hemispherectomies remove the affected hemisphere whereas functional
hemispherectomies only remove parts of the affected hemisphere as well as cutting the corpus
callosum.
• The procedures are generally used for uncontrolled epilepsy.
• Candidates for these types of surgeries include people who do not experience improvement in
their condition after taking medication and who have severe, uncontrollable seizures beginning
in a non-functioning hemisphere.
• Prior to surgery, EEGs, seizure monitoring, an MRI, and WADA test, are done to determine
which hemisphere is dominant for critical functions such as speech and memory.
• During surgery, an incision is made in the scalp, a piece of bone is removed and a section of the
dura is pulled back. Surgical microscopes are utilized to give the surgeon a magnified view of
the brain structures. The surgeon removes portions of the affected hemisphere, often taking all of
the temporal lobe but leaving the frontal and parietal lobes. The surgeon also separates the
hemispheres to access and cut the corpus callosum. After the tissue is removed, the dura and
bone are fixed back into place, and the scalp is closed using stitches or staples.
• After the surgery, the hospital stay is about a week. Most patients can return to normal
activities within 6 to 8 weeks.
• 85 % of patients will have a reduction in seizures and 60 % will have no seizures.
side effects of this surgery can include scalp numbness, trouble remembering names or words,
muscle weakness on the affected side, headaches, fatigues, and depression.
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